Shared Projects by dr2chase

Constant-current draw from bicycle dynamo into LEDs and 5V supply, 5V supply has priority

Bicycle hub power distribution – some to LEDs, some to USB, includes microcontroller and switches for directing LED current.

Parts list

Software (still under development)

A modified optional Greinacher doubler. To build, needs 4 SB540 (or similar) diodes, 2 1000uF x 16V caps, 1 10k-22k uF x 16V cap, optional 3.5mm terminal block, and an optional jumper (you want the jumper, but it’s optional in case you know better or want to play games switching it on and off).

Big cap solders on to the end, use epoxy to prevent flex, and jumper activates doubler. Pictures

Modified Greinacher doubler, 3 by ¾ diameter (plus extra shim). Intended to use SB540 diodes (they’re large, but they are intended to physically butt against the smaller capacitors) and 16V electrolytic caps, preferably Digikey parts

http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail&itemSeq=150331853 (8mm diameter, 5mm lead spacing, 1000 uF)

and

http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail&itemSeq=150249397 (18mm diameter, 7.5mm lead spacing, 10000 uF).

The central connections are sized to allow use of either 14 gauge wire or 1/16 inch tubing; the tubing would allow you to connect the two boards, and mount a 3.5mm terminal block across the four holes (AC input on the inside, DC output on the outside).

The circuitless board is intended to fit between the large end capacitor and the board to which it connects, to prevent inadvertent shorts to the other connections on that board.

The intended assembly order is (1) solder diodes and wires to the underside of the mostly-circular board, trimming connections on the top side, (2) fit circuitless shield and then solder large capacitor into place, (3) fit small capacitors etc into irregular board, perhaps shimming/shield with kapton tape, and (4) solder irregular board into place.

It is best to position the diodes closer to the round board, but still leaving enough so that there is enough room for them to connect to the irregular board with clearance for the smaller caps. This is so that the tops of the capacitors will be wedged against the diodes with less chance for wiggling.

This is suitable for powering between 1 and 4 power LEDs in series (4 x 3.5V Vf is 14 volts, the caps are rated at 16 volts, don’t push your luck). The power source is AC from either a sidewall or hub dynamo; both of these are inherently current-limited so it is not possible to burn out the LEDs. Any on/off switch inserted into the circuit should be on the AC (power input) side; removing the DC load will result in high voltages exceeding the ratings of the capacitors. Care should be taken using this to supply a switching power supply, because those can also “refuse current”, which will also result in high voltages (and the higher the voltage, the more current they refuse).

Modified Greinacher doubler, skinny. Intended to convert bicycle “generator” (sidewall or hub) to LED current. Recommend four SB540 diodes, two 1mF x 16V laid down on board, one 6.8mF x 35V at end. Be aware of dimensions to be sure it will fit in desired tube. Use painter’s tape to make mold for epoxy poured around top of end diode. Note that there are extra V+ and V- holes. Bicycle “generators” are naturally current-limited so V+ and V- can be connected directly to power LEDs in series. IMPORTANT - do not disconnect from load while connected to bicycle generator.